This invention relates to slant axis rotary mechanisms such as compressors, engines, pumps or the like. More specifically, the invention relates to improvements in such a mechanism to increase the fatigue life of the mechanism main shaft and bearings associated therewith.
The power output of a slant axis rotary mechanism employed as an engine is limited by bending stresses in the fillets of the mainshaft where the mainshaft joins the angularly offset portion or eccentric thereof. Similarly, the operating efficiency of such mechanisms operating as pumps or compressors is also limited.
The cause of the problem is two-fold. In a slant axis rotary mechanism, there is a large span between the mainshaft bearings which often is in excess of the hub sphere diameter of the rotor. In addition, a relatively small shaft diameter is employed, with the result that there is a large stress concentration at the fillets. Because, during operation of such mechanisms, there is a complete stress reversal fatigue life may be severely reduced.
As is well known, such mechanisms typically employ a thrust bearing on one end of the mainshaft. Thrust loads imposed on such a thrust bearing during operation of slant axis rotary mechanisms are rather large. Thus, a rather large thrust bearing must be employed and the same must be manufactured with high tolerance to insure proper operation.